Nothing fancy. Beer, lots of it. That and bum on seat – fingers on keyboard.
More seriously, it’s a crisis of self-doubt and/or self-pity. The ultimate blue funk. I’ll often try to edit part of my work. If my brain’s in edit mode rather than create mode that often assuages it. I’ll write an outline rather than details. I’ll sometimes put the project away and look at another one. Sometimes the block is telling me “this is rubbish” and it takes distance to see why.
If all else fails, I go for a walk or boat or play my guitar. The later often transfers the block to those around me, so it’s a last resort.